WSP04463

• File Number: 8460.500
• Description: Platte River Recovery Plan
• Basin: South Platte
• Date: 6/1/1997
• Author: Colo Div of Wildlife
• Title: Inventory and Status of South Platte River Native Fishes in Colorado
• Water Supply Pro - Doc Type: Publication

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Primary limiting factors of the Plum Creek drainage within Hydrounit 10190002 are land
development and resulting habitat degradation and loss of quality aquatic habitats. Grazing is also
exerting a negative impact in certain areas. West Plum Creek, however, is largely comprised of
unmodified transition zone stream reaches, and contains high quality aquatic habitats. The rest of
the northern plains portion of this drainage is affected by urban runoff, point and nonpoint
pollution, industrial uses and other impacts common ofurban development. East Plum Creek is
limited by low flows, minimal riparian buffer zones in some reaches, and lack of substrate
variability (a large percentage is composed of shifting sand). Additionally, a gravel mining
operation on lower East Plum Creek creates very turbid conditions downstream. The Plum Creek
mainstem is characterized by monotonous stream channel morphology: wide, shallow, shifting
sandy substrates lacking physical habitat variability.

The constructed ponds located above Chatfield Reservoir are impacted by nutrient
enriched effluent. Water quality analyses showed elevated levels of ammonia, cWoride, sulfate,
and extremely high conductivities. The ponds are characterized by mostly sand and silt substrates,
minimal aquatic vegetation, and no riparian cover.

Several issues currently pose potentially significant impacts for special concern fishes in
the Plum Creek drainage. The property where northern redbelly dace populations exist is
currently for sale, with water rights being litigated in court. One of these populations is
dependent upon diverted Garber Creek water. Possible alternatives to protect these populations
of northern redbelly dace include purchase or lease of the land and water rights via GOCO
funding, creation of partnerships with the landowners to maintain conservation easements into
perpetuity (CDOW is currently negotiating a Memorandum of Understanding and Access
Agreement with the landowner), and possible transplantation of this species to other suitable,
better-protected habitats. This is a high priority drainage with respect to diversity of native fish
species and the presence of several special status species. Further surveys for other potential
special concern populations should be conducted and development of private land partnerships
should be initiated.

MIDDLE SOUTH PLATTE DRAINAGE - HYDROUNIT 10190003
The middle South Platte drainage is a higWy complex drainage within the South Platte
River Basin. It encompasses a total of 2906 square miles. The drainage originates in the foothills
southeast of Castle Rock, and includes most of metropolitan Denver and the heavily urbanized
and industrialized sLlburbs of Aurora, Commerce City, Northglenn, Thornton, and Broomfield. It
also includes a large expanse of prairie to the east and south of Denver. All of these drainages
enter the mainstem near Brighton and Fort Lupton. The mainstem river then adds the inflow from
the St. Vrain, Big Thompson, and Poudre rivers near Greeley; makes an abrupt bend eastward
and subsequently receives the drainage from the prairie and irrigated farmland north and east of
Denver including the areas around Hudson, Roggen, Platteville, Watkins, and Bennett. As the
river continues east, this hydrounit includes the large off-channel impoundments of Empire,
Jackson and Riverside reservoirs. It also drains an inverted "V" shaped piece ofIand to the north
of those reservoirs encompassing approximately 80 square miles.

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